grove: add grove temperature sensor support and example

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/grove/grove.cxx

@@ -22,10 +22,15 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <iostream>
+
 #include "grove.h"
+#include "math.h"
 
 using namespace upm;
 
+//// GroveLed ////
+
 GroveLed::GroveLed(int pin)
 {
     maa_init();
@@ -56,3 +61,30 @@ maa_result_t GroveLed::off()
 {
     return write(0);
 }
+
+//// GroveTemp ////
+
+GroveTemp::GroveTemp(unsigned int pin)
+{
+    maa_init();
+    m_aio = maa_aio_init(pin);
+    m_name = "Temperature Sensor";
+}
+
+GroveTemp::~GroveTemp()
+{
+    maa_aio_close(m_aio);
+}
+
+int GroveTemp::value ()
+{
+    int a = maa_aio_read_u16(m_aio);
+    float r = (float)(1023-a)*10000/a;
+    float t = 1/(logf(r/10000)/3975 + 1/298.15)-273.15;
+    return (int) t;
+}
+
+float GroveTemp::raw_value()
+{
+    return (float) maa_aio_read_u16(m_aio);
+}